He says the engine could provide five times as much power as a laptop battery for the same cost.

"My laptop battery now runs my computer for about three hours before recharging. A microengine power system, engine plus fuel, with the same weight as the battery should run the laptop for 15 to 20 hours before refuelling," says Epstein.

The engine works on the same principle as a jet engine.

A compressor sucks in air from the outside and compresses the air. Fuel injectors add fuel to the compressed air and the mixture gets ignited.

Epstein's engine will run on a variety of fuel, including kerosene, propane, ethanol, methanol or hydrogen.

The hot gas produced expands rapidly to turn a turbine, which turns a coil inside a magnet to generate electricity.

A jet engine has thousands of parts assembled into the few components that comprise the compressor, combustion chamber and turbine.

Epstein's microengine only has two parts: a moveable rotor and a stationary structure that together function as the compressor and combustor.

And this jet engine would fit into a matchbox. The compression chamber is about the size of a pencil eraser, the fuel injectors are pen-point holes and the turbine is about the size of a 10 cent piece.

Manufacturing on a small scale

Such teeny components require a much different manufacturing process than large-scale jet engine parts.

Epstein and his team, like other researchers in this field, turn to the field of microelectromechanical systems, or MEMS, which is used to fabricate miniature devices ranging from computer chips and biological sensors to chemical processors.

They etch out the parts from wafers of silicon. The etching requires incredible accuracy with little or no room for error.

"They are bringing the field of MEMs to levels that a few years ago would have seemed impossible," says Carlos Fernandez-Pello, a professor of mechanical engineering at the University of California, Berkeley.

Like a car engine

Pello's team is working on a similar micro system that works like a car engine.

A bigger challenge for Epstein may be getting the individual components to work as a single engine, says Pello.

At that tiny scale, the heat produced can spread across the whole device, causing parts to expand and not work well.

But if they can find a way to insulate the combustor from the other components, a final working product would be about the size of a cigarette lighter, with the engine on top and the fuel below.

"The size of that [cigarette] lighter is the size of two AA batteries. But the time it would give you power, it's potentially 100 times more ... maybe 50 or 60 hours," says Pello.

Such a microengine would be as safe as a pocket lighter, too, he says.

How about emissions?

Epstein says that his microengine will produce one-hundredth the emissions that a rechargeable laptop battery produces indirectly during the recharging stage, as it draws electricity from the grid.

So far, the microengineered components have been micromachined, tested individually and assembled into the 20 cent piece-sized test engines.

Now the team has to add fuel and demonstrate a working engine, something Epstein thinks can be accomplished within the next 12 months.